This application claims the priority of German application 196 51 417.7 filed in Germany on Nov. 11, 1996, the disclosure of which is expressly incorporated by reference herein.
The present invention relates to an opening device for open-end spinning machines comprising an opening roller which rotates in a housing under a vacuum and which is sealed from the housing in the area of a front side exposed to the free atmosphere by means of a labyrinth seal. The labyrinth seal starts in the area of a peripheral combing means of the opening roller with a sealing gap in the form of an annular clearance and ends with a second sealing gap arranged at a distance from the first sealing gap, said second sealing gap being connected directly to the free atmosphere and taking the form of an annular clearance, whereby these sealing gaps are formed by a first and second cylindrical collar surface of the opening roller and corresponding hollow cylindrical countersurfaces of the housing.
In the case of an opening device of this type (U.S. Pat. No. 3,800,520, FIG. 6), the sealing gaps of the labyrinth seal permit a certain small amount of air to flow from the atmosphere to the combing structure. As, however, experience has shown, single fibers tend, in the area at the open atmosphere and also in the area of the combing structure, to penetrate from the outside into the labyrinth seal and therefore there is the risk that the labyrinth seal may become blocked with fly accumulation after a time. The opening roller must then be stopped, disassembled and cleaned.
It is an object of the present invention to avoid this disadvantage to a large extent and to create an opening device wherein the fly accumulation is to a large extent kept away from the labyrinth seal.
This object has been achieved in accordance with the present invention in that the first collar surface arranged at the first sealing gap and the second collar surface arranged at the second sealing gap are provided with fly-repulsing notches, whose direction of effect is directed away from the labyrinth seal.
In particular, the direction of effect of the notches of the first collar surface is towards the combing structure and the direction of effect of the notches of the second collar surface is towards the open atmosphere. This results in the fly coming from the combing structure being knocked back again to the combing means and the fibers which are found flying around in the open atmosphere are returned thereto.
The fly-repulsing notches themselves take the form of grooves extending diagonally to the rotational direction of the opening roller, and have--in cross section--a striker surface on each side facing away from the rotational direction, which striker surface extends radially to the opening roller. For reasons of redressing the state of unbalance, a plurality of notches, preferably three or four, are arranged on each collar surface. In order that the sealing effect of the labyrinth seal is increased, the first and second collar surfaces comprising the notches have differing diameters. Hereby it can be provided that the first and second sealing gaps are separated by at least one expansion chamber in the form of an annular chamber.
In an advantageous embodiment of the present invention, the first and the second collar surfaces are arranged on the same component, which can be separated from the opening roller. This component is, for example, a tension disc, with which a ring, comprising the combing structure, is slid onto a base body of the opening roller.